DE 199 17 268 A1 describes a method for testing an electromagnetic flowmeter and a flowmeter. The flowmeter has a measuring tube and a coil arrangement which generates a magnetic field at right angles to the direction of flow through the measuring tube, wherein the direction of the current flowing through the coil arrangement is periodically varied. In order to enable easy testing of the flowmeter, following a change in the direction of the current, at least one parameter of the current rise, for example, the rise time is determined and compared with a reference value. Provided the flowmeter is able to operate unimpeded and error-free, the rise shapes are practically identical, with a very small scatter. Only when an error of an electrical or magnetic nature occurs does the rise shape change. This change is a sign that the flowmeter possibly delivers imprecise measuring results and needs to be more closely examined or exchanged. This examination can take place during measurement of a flow. This has the advantage that the flow metering does not have to be interrupted for testing the flowmeter and that the flowmeter is able to perform testing of its function continuously or permanently. The flowmeter can be tested in precisely the condition in which it functions during normal operation. It is also known from the cited document, following switching of the current direction, to use a raised voltage, which is also known as the boost voltage. This accelerates the build-up of the magnetic field and also permits the actual measurement to be made in shorter measuring periods. When the desired current strength in the coil arrangement has been reached, the voltage is reduced and switching-over to regulation of a constant current in the coil arrangement takes place. With a constant current in the coil arrangement, in an ideal electromagnetic flowmeter, it would be possible to measure a voltage at the measuring electrodes that is directly proportional to the velocity of the medium flowing through the measuring tube. In practice, however, flowmeters are subject to measuring errors and these can be divided into two components: linearity errors and offset errors. Offset errors can also be referred to as zero point errors.